Multi-scale Investigations of the Environmental Transformation, Fate and Inhibitory Effects of Engineered Nanoparticles

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Engineered nanoparticles (ENPs) such as carbon nanotubes, silver nanoparticles (nAg), and metal oxides can now be found in over 1000 commercial products. Despite the numerous anticipated benefits of nanotechnology, there is great concern that we do not yet fully understand the environmental and health risks associated with this revolution. Currently, there are no ENP-specific regulations in effect in Canada, and environmental and public health protection agencies are scrambling to gather the data required to address the safety and regulatory questions related to nanotechnology. The U.S. National Research Council recently proposed a new research strategy for environmental, health, and safety (EH&S) aspects of ENPs, recommending that research should focus on critical elements such as physical, chemical, and biological transformations that will ultimately control ENP persistence, bioavailability, reactivity, and toxicity. The complex and dynamic nature of these transformations complicates our ability to predict the risks associated with the release of ENPs in our environment. Building on the outcomes of my previous NSERC Discovery grant, the 5-year goal of the proposed research program is to establish the impacts of common physical, chemical, and biological transformations on the transport, fate and inhibitory effects of selected ENPs in soil and aquatic environments. The proposed work is the first to systematically examine the complex effects of different physical, chemical and biological transformations on ENP fate and impacts at relevant long-term exposure times. The research will focus on two of the ENPs that are found in largest number of commercial products (nAg) or produced in the largest quantities (nTiO2). The long-term objective of the research program is to make influential contributions to global efforts to identify and quantify the environmental and public health risks associated with ENPs. Our research will provide the knowledgebase and the resources to pursue innovative research on colloidal phenomena in aqueous systems. Clearly, the potential impact of the research spans over a broad range of industrial, environmental and biomedical applications. The scientific approach will include controlled laboratory studies of ENP aggregation, dissolution, transport and inhibition/toxicity using state-of-the-art experimental techniques, including single-particle-inductively coupled plasma mass spectrometry, nanoparticle tracking analysis, quartz crystal microbalance with dissipation monitoring, and hyperspectral imaging with enhanced darkfield microscopy. By systematically varying key environmental conditions and ENP properties (e.g., size, surface coating chemistry, core chemistry), we will develop functional relationships between measurable parameters and target end-points of EH&S risk assessment. To relate these controlled laboratory experiments to natural conditions, studies will also be conducted using soils and groundwater collected from Canadian geographical locations. This research with ENPs having carefully controlled but variable surface functionalization, sizes and core properties will make significant transformative contributions in supporting global environmental risk assessment efforts. The results of this research will be critical to Canadian ENP producers for the development of safe ENPs. The proposed research program prioritizes the training of HQP using an integrated multidisciplinary approach and a collaborative training environment. At least 3 Ph.D., 3 M.Eng., and 5 undergraduates will be integrated into a large research team where there is extensive existing experience. Students trained through this program will be of great value in the Canadian workforce in emerging areas of engineering and applied science.